设计模式--简单工厂模式

面向对象语言的封装，继承和多态属性的应用。来自《大话设计模式》，java 实现

Operator.java文件中，基类。

public class Operator
{
float num1 ;
float num2;
float result;
public float getNum1()
{
return num1;
}
public void setNum1(float num1)
{
this.num1 = num1;
}

public float getNum2()
{
return num2;
}
public void setNum2(float num2)
{
this.num2 = num2;
}

public float getResult()
{
return result;
}

}

AddOperator .java实现加法运算。

public class AddOperator extends Operator
{
    public float getResult()
{
    return num1 + num2;
}
}

MulOperator .java实现乘法运算。

public class MulOperator extends Operator
{
    public float getResult()
{
return num1 * num2;
}
}

工厂类OperateFactory.java，创建对象。

public class OperateFactory
{
public static Operator createOperator(String operator)
{
Operator oper = null;
switch (operator)
{
case "+":
oper = new AddOperator();
break;
case "*":
oper = new MulOperator();
break;
default:
break;
}
return oper;

}
}

测试类Test.java

public class Test
{
    public static void main(String[] args) throws Throwable
    {
     
      Operator oper = null ;
      oper = OperateFactory.createOperator("+");
      oper.num1 = 1;
      oper.num2 = 2;
      System.out.println(oper.getResult());
      
    }

}

当需要新增除法运算时，只需新建除法类，在工厂中创建该类的对象。对其他类并不影响。